a) Field of the Invention
The invention is directed to electrostatic deflection systems for corpuscular radiation which can be used particularly for microstructured and nanostructured applications in lithography installations or measuring equipment (e.g., REM).
b) Description of the Related Art
For processes such as those mentioned above, it is desirable to have the capability for high-precision deflection of charged corpuscles, particularly electrons with a small time constant. Further, a deflection system of this type should have only a small space requirement so that it can be installed in favorable positions in the electron-optical installation.
DE 199 30 234 A1 discloses an electrostatic deflection device in which the rod-shaped electrode elements are arranged inside a holding device The individual electrode elements are produced from a conductive ceramic material with a predetermined specific resistance. The holding device is constructed as a hollow cylindrical tube. The individual electrode elements are then inserted into the holding device in a desired axially symmetric arrangement and are connected to the holding device by material bonding.
In this connection, it has turned out that the adjustment accuracy required for a high-precision deflection of a corpuscular beam when the individual electrode elements are arranged relative to one another so as to maintain exact axial symmetry cannot be met during assembly on the one hand and, on the other hand, connection by material bonding leads to deviations in the positioning of the individual electrode elements at the holding device. The material-bonding connection is produced by spot-soldered or glued connections through openings formed in the holder.
Deflection systems should also be suitable for use in rapidly changing magnetic fields, which is advantageous for low-aberration electron-optical solutions.
Deflection devices for electron beams which are not easily reproducible can also be produced in this form.
Further, deflection systems in which the individual electrodes are formed of tensioned wires are also known as is described, for example, in EP 1 033 738 A1. The wires, to which tensile force is applied, form weak points particularly in that they are exposed to high mechanical loads at their material-bonded connection points which can result in detachment or in different pretensioning.
Further, the wires forming individual electrodes can have deviations in electrical parameters which lead to inhomogeneity in the electrical fields that can be used for the deflection of electron beams.